1. Field of the Invention
The present invention relates to a positioning structure of a roller, and in particular to a positioning structure of a roller for use in an auto document feed apparatus that can provide a driven roller for being securely contacted with an active roller.
2. Description of the Prior Art
Please refer to the FIG. 1 and FIG. 2, a positioning structure of a roller adapted for auto document feed apparatus according to the prior art is shown as reference number 1, which is arranged in such as a printer, an auto document feed and fax machine, etc. A support portion 11 is arranged on a plastic plate (not shown) of the auto document feed apparatus. The support portion 11 has an opening 12. A metal rod 13 is passed through the opening 12 and arranged on the support portion 11. A driven roller 14 is sleeved on the metal rod 13, for contacting an active roller (not shown). A spring 15 is positioned in the opening 12 under the metal rod 13, to against the metal rod 13.
FIG. 3 and FIG. 4 show another embodiment of the prior art, a positioning structure of a roller adapted for auto document feed apparatus according to the prior art is shown as reference number 2. A support portion 21 is arranged on a plastic plate (not shown) of the auto document feed apparatus. The support portion 21 has an opening 22. A metal rod 23 is passed through the opening 22 and arranged on the support portion 21. A driven roller 24 is sleeved on the metal rod 23, for contacting an active roller (not shown). A screw 26 locked a spring band 25 on the plastic plate (not shown) to deliver paper.
However, due to some manufacture technology limitations and the consideration of manufacturing cost, the positioning structure of roller adapted for auto document feed apparatus can not be easily fabricated and maintained. Therefore, the manufacturing cost will be increased.
In addition, the conventional positioning structure of a roller adapted for auto document feed apparatus is unfavorable to repair, replace and maintain. Furthermore, the manufacturing cost and the difficulty of fabrication are high, too.
Further, in accordance with the Mechanical Engineering, when a force is pressured on a non-uniform shaft or a different element on the shaft, a torque or a bending moment will be generated. Therefore, it would cause the angular velocity to be different between the driven roller and the active roller, make the paper block up, and even deform or break the shaft.
Accordingly, the positioning structure of a roller adapted for auto document feed apparatus known in the prior art is non-convenient when used.
Therefore, the present invention is directed to an improved positioning structure of a roller adapted for auto document feed apparatus having a reasonable design and lower manufactured cost thereon.